Objective To explore the folic acid and adult neural stem cells’ joint influencing mechanism on the rat with Traumatic Brain Injury, and to find out its possible mechanism. Methods Divide 120 rats to 6 groups randomly—normal group, mode group, sham operation group, folacin injection group, adult stem cells transplant group, and folacin injection plus adult stem cells transplant group. Observe the morphological change under the microscope, then, do flow cytometry test and detect the expression of the neural stem cells’ facial notation—CD105、CD45、CD44、CD29. Examine the expression of neuron special enolase( NSE) and the expression of gelatinous fibre acidic protein (GFAP) with immunofluorescence. Examine the rats’ ability to motor-coordinate and conform with balance beam. Test each group’s learning and memorizing ability by conducting the Morris water maze experiment. Then, conduct the HE chromosome and Brdu immunohistochemistry experiment to detect morphological change of the brain tissue. After this, do the enzyme-linked immunosorbent assay (ELISA) to detect the expression of brain-derived neurotrophic factor( BDNF) and the expression of nerve growth factor. The last but not least, use western blotting to examine the expression of related dead protein in the brain tissue:BCL-2、Bax、Caspase-3. ResultsThe separated cells can be vitro subcultured, by doing flow cytometry test, we find that positive cells express CD44 and CD29 while negative express CD105, CD45. Cells induced by fetal bovine serum can produce NSE or GFAP positive cells. Experiments suggest that traumatic brain injured rats can significantly improve their behavior after jointly influenced by the folic acid and adult neural stem cells. Besides, they can also reduce brain tissue inflammation, restore damaged nerve cells, increase brain tissue of BDNF and NGF''s content, increase BCL 2 expression, and lower the expression of Bax, caspase-3. Conclusion The folic acid combined with adult neural stem cell intervention in traumatic brain injury in rats can significantly improve the central nervous system dysfunction, plays an important role to maintain the steady microenvironment in the neuron.